1. Field of the Invention
The present invention relates to a method for producing an integrated heat exchanger in which a plurality of heat exchangers each having a heat radiation fin are coupled to each other in a stacking direction, and to an integrated heat exchanger produced by such a method.
2. Description of the Related Art
As shown in FIG. 14, an integrated heat exchanger according to a related art includes, for example, a radiator 1 and a condenser 2, which are coupled to each other in a stacking direction. The radiator 1 cools cooling water for an engine. The condenser 2 is used in a refrigeration cycle of an air conditioner.
The radiator 1 and the condenser 2 have pairs of tanks 3 and 3a, and 4 and 4a, which are called headers, respectively. The radiator 1 and the condenser 2 have a structure in which a plurality of tubes 5 communicate between the tanks 3 and 3a and between 4 and 4a, and fins 6 are interposed between the tubes 5 to be joined thereto. In the figure, the tubes and the fins of the condenser 2 are not shown.
Each of the fins 6, which are used in the radiator 1 and the condenser 2 is configured as a louver fin as shown in FIG. 15. A strip thin sheet P of aluminum is formed into a corrugated shape (bellows-like shape) in which bent portions 6a and flat portions 6b are alternately continued. A plurality of louvers 7 are punched and raised in each of the flat portions 6b along a longitudinal direction Y of the strip thin sheet P to be juxtaposed in a lateral direction X of the strip thin sheet P.
If the punched and raised directions of the louvers 7 of the louver fin 6 are unbalanced in the lateral, direction X, the whole of the louver fin 6 is curved and rounded as shown in FIG. 16 by difference in amount of distortion generated in the raised portions.
As shown in FIG. 15, therefore, the louvers 7 are formed in the flat portions 6b so as to be symmetrical in number and the raised direction (opening direction) with respect to a center portion in the lateral direction X, so that the distortion amounts are balanced in the lateral direction X. Whereby the louver fin 6 can be prevented from being curved.
On the other hand, in the fins 6, which are to be incorporated into the radiator 1 and the condenser 2 of the integrated heat exchanger, it is preferable to set the opening directions of the louvers 7 in each of the heat exchangers constant in order to reduce the flow resistance of the air.
In order to set the opening directions of the louvers 7 constant while preventing the fin 6 to be incorporated into the radiator 1 and the condenser 2 from being curved, therefore, one side portion A in the lateral direction X of the louver fin 6 shown in FIG. 15 can be used in the radiator 1, and the other side portion B can be used in the condenser 2. In this case, the fin of the radiator 1, and that of the condenser 2 are formed in a state where the fins are connected to each other across the center portion in the lateral direction X.
However, when the louver fin 6 in which the fins (the portions A and B) are formed are attached to the radiator 1 and the condenser 2 of the integrated heat exchanger, a state is caused where the fin (the portion A) of the radiator 1 is connected to the fin (the portion B) of the condenser 2. Consequently, the heat of the radiator 1 flows into the condenser 2 through the connecting portion, thereby lowering the heat exchange efficiency of the condenser 2.
Therefore, a technique is attempted in which, although not shown, a slit is formed in the connecting portion to reduce the amount of heat conduction. Also in this case where a slit is formed, in order to prevent the louver fin 6 from being curved, it is essential to connect the fin of the portion A with that of the portion B. As a result, connecting portions are formed at adequate intervals in the slit, and heat conduction is performed through the connecting portions.